Kali linux changing boot time in direct boot as well as virtually and change boot menu picture #customization

1.Boot

Go to dir

cd /etc/default/

nano grub - change 5 to 2 (or how much sec you want to boot your machine)

then

update-grup

and you can change your boot menu no. to.

/usr/share/grub/themes/kali - change the boot menu picture.

2.Virtually